Grace to you and peace from him who is and who was and who is to come, and from the seven spirits who are before his throne, and from Jesus Christ the faithful witness, the firstborn of the dead, and the ruler of kings on earth.
To him who loves us and has freed us from our sins by his blood and made us a kingdom, priests to his God and Father, to him be glory and dominion forever and ever. Amen. Behold, he is coming with the clouds, and every eye will see him, even those who pierced him, and all tribes of the earth will wail on account of him. Even so. Amen.
“I am the Alpha and the Omega,” says the Lord God, “who is and who was and who is to come, the Almighty.”
The Eternal Advent, that is, God--He who was, who is, and who is to come. Fr. Yves Congar, O.P, notes in The Word and the Spirit, that the Hebrew word for 'truth' comes from the verb that means to be stable, firm, sure, reliable, and that in the 132 times it is used in the Old Testament, more than half are used of God. The concepts of truth and faithfulness (steadfastness) are therefore linked, and they are rooted in God's very being.
"I am who I shall be" is, according to the TOB, a more favorable rendering of the name God reveals of himself in the burning bush (more commonly "I am who I am"). In this rendering we see an echo of Revelation above--God was, God is, and God will be, He who is to come, and always will be to come.
While the primary mode of Advent is anticipation of the celebration of the Incarnate Word's Nativity, we know it also is a time to reflect on His Second Coming, and in the above Scripture, we see also that it can also be a time of reflection on God in Himself, a coming of Being that will always be. This is a joyful anticipation that we always have had, we have now, and will have in eternity. God is sure. He will always be. What a great joy it is to know this!
So let us now welcome God, in union with the Word and Spirit:
The Spirit and the Bride say, “Come.” And let the one who hears say, “Come.” And let the one who is thirsty come; let the one who desires take the water of life without price. (Rev 22:17)